Let me fire a round here.
Ask the question why is the Prospect and Endurance not used vs the Venture.
Most players will focus on the Barges first just because of the mass ore intake. Although the Prospect and Endurance can be on par by m3 intake easily if Max-Min.
Prospect can do a about ~3650m3 intake [maximum theoretical possible] But that is T2 Modulated Deep Core Miners.
Endurance is a bit lower ~3200m3 intake [maximum theoretical possible] with T2 But you have to remember Endurance is a Drone Capable ship. So you can field a flight of three mining drones as well. So about the same intake as Prospect in mining about ish. Into 4000m3 range if you buff the drones.
Prospect can be also adjusted to ludricious small signature size by skills and Halo implants down to 24m which is the size of a Capsule. And it gets smaller in Wolf-Rayet WH. And I think Instinct adjusts it even further.
Endurance is a bit more wonky because at full navigation skill, and under basic cloak its probably the fasted “stealth ship” If equipped with a Halo Miner setup. These ships are really hard to catch. And if you prop mod them with deadspace AB they can out speed most threats at a freakish level never mind MWD. I have gotten the Endurance to 3km/s with AB on. Also the speed of the ship makes alot of NPC miss. Which is when I like to talk about ‘NPC Recruiting’ Because if you fit this ship to have scrams/stabs you can pin an attacker down for the NPC pummel while you make a getaway.
The other funny thing is Prospects and Endurances get even more crazy under boost. An Omnivore+Yeti-Implant Endurance can get its Ice Mining lasers down to like 26.5sec cycle under boost 48 sec base adjusted down. [And remember an Endurance is literally a Micro Skiff with 15,000m3 ore hold.] Which makes it the king of High Sec Ice Collection.
Prospect though is a bit more nuanced. Because it is a ore miner but also a gas miner as well. But the real interest is the gas mining capacities. Which can both be tweaked under boost. I have looked at the adjustments of gas cycle times inside [with Tier II mind you of literally 22sec.] Also same gas miners can be even range boosted by implants and boost as well!
The problem I have is the Venture and Prospect are equal in gas mining capacity. There is no benefit up or down. A Venture has an inate Warp Core Stab which can be boosted to +3 with an additional Warp Core. Industrial Cyno is avail. Venture can also with its rigs actually become a drone boat, and its mining drone boosts literally have the mining drones out performing most of its miners. You can fit a Venture to do Multi-role. Mining or Gas +Scanning+Relic/Data all in one ship. For a fairly low cost.
So why would I get a Prospect over a Venture?
Prospect only has 3 upper slots. [One of which must be covert cloak] + 2 slots for Ore/Ice Miners/Salvagers/Gas Miners. So it becomes a juggling game because you can carry a Depot with a Prospect. But the Prospects Cargo size aids in being modulated miner equipped. Which the Venture has to be very careful with. So you can adjust in field from mining to gas to ice as needed. Or if necessary Cyno / Combat. Prospect feels like “ORE Interceptor” and has been used as such. With its shields and cloak allowing it to interdict other ships maybe carrying out the same activities. But with no drones you have some serious downsides vs the Endurance and Venture which can buff their drones with rigs. Sometimes Insanely so. Also Prospect is weirdly 10,000m3 [No other Ore ship has this cargo size for some reason]
Endurance on the other hand feels a bit more deliberately multirole. As in you can Ice/Mine with it easily its ore mining bonus of 300% is nothing to sneeze at. Its innate speed bonuses mean you have to kind of carefully finesse drone operations because even speed adjusted mining drones struggle to keep up with it without AB on during orbits around mining rocks.
Your three upper slots can be adjusted in a bewildering array of variable builds to maximize the ships capacity. And you can carry a mobile depot and equipment in your much more comfortable sized cargo bay vs. the Prospect which means you can swap out even more aggressively. It can support some very effective multirole builds. And with a 15,000m3 ore hold is on par with a Skiff. Kind of displacing the Skiff in many fields, due to competitive pricing. Rapid Ice mining capacity buffed by Omnivores allows a player in Highsec to crush the Barge competition with or without boosts. [I actually surprised an Orca Boosting Multi-box player by keeping parity in collection of Ice. He had 200 units of Ice after Ice Mining Drone and Boosted Hulks. I had 150 units of Ice over the same time period. Granted I have to offload it more often. So some time lost there.] Boosted Prospect can possibly do twice as fast with two Ice Miners and Omnivores. But the Capacitor and CPU limit the number you can field vs. Endurance. And having a 10,000m3 cargo hold vs. 15km3 cargo hold.
The problem is this. Prospect is equivalent in Gas Collection to a Venture, and Endurance although having Ice Collection bonuses isn’t really good at Gas Collection. So price wise Prospect and Endurance already are overlooked mostly on cost and due the fact the Venture can already do what they can do easily. Now a boosted Prospect and Endurance in Ore and Ice mining is insanely good. But the high resource areas in the game require boosting ships which attracts attention. [Notice I said boosting ships…ie Command Destroyers/BCs etc. Before even waving the Porpoise/Orca/Rocqual around.]
Also the Ventures innate warp core stabs also make it really really beneficial. And as a players skills increase this advantage becomes more apparent. A Venture with an Additional Warpcore Stab is a really tough item to catch. Even as their skills increase. The Prospect and Endurance to “compete” by adding +4 Warp Core Stabs [Prospect] and +3 Warp Core Stabs [Endurance] Which forces the players to “Face Plant” their prospective Expeditions into materials to get locks, which then is extremely slow. Warp Core Stabs have negative effects on signature resolution and lock range which slows down locks. Also the Venture having 3 Rig slots vs. Prospect and Endurances 2 Rig Slots gives it some very insane bonuses to certain fields allowing the ship out outshine both in various nuanced ways.
Also the Expedition Frigates also are borked by an issue of their requirement skills being longer than Barges. So Barges tend to be looked at first vs. Expedition Ships. And also that most higher efficiency miners are available a Lv IV where a Strip Miner can be avail to an Alpha Player at T1. [Further Incentivizing their drive to barges.] Also the issue of covert op cloak and cloaking does slow down expedition frigate training.
I Believe though the Prospect needs an edge over the Venture in Gas Mining. Just a small edge. Either in gas miner cycle speed or intake increase. So its more apt to be chosen over a Venture once the Skills are trained.
The Endurance could also do with a Gas Mining intake bonus. So its not left out of the fun. Although it would not have a gas mining bonus to cycle speed. But the amount taken in. Slower but more gas. And the Endurance would have the capacity.
But remember the rats spawn in WH space after a set time so this becomes a careful dance. And LS is another matter all together.
Although I have to be honest I would like to see an in between ship between the Venture and Barge so to force a bit of a slow down mode for Barge Skill Training. So then a player has to think which route he wants to take. And having this in between ship avail for Alphas would allow you to use T1 Alpha Strips at the get go albeit it would be ore hold cargo space than a barge. Also having some sort of boosted in between variant of the mining frigate between the Venture and the Expeditions would also interest the players in going that route. [I was thinking a Venture variant much like the four mining laser slot NPC mining Frigates I see on a consistent basis.]
Also to note some items are well rounded in pick up. So a Venture can carry 1000units of [any type of Gneiss ] at 5000m3 ore hold. Prospect can carry 2000 units of Gneiss at 10,000m3 ore hold. And Endurance can carry 3000 units of Gneiss at 15,000m3. Remember Endurance is equivalent to a Skiff.
But the OP has a point some areas of the ship trees are left out because the magnetic draw of certain specific ships and their fairly on face economic advantages in the game. And with your skills going up some attributes of even T1 ships start to directly compete with T2 ships for player interest or economic viability. This being extremely important to overall skill investment and use of Plex/Omega etc.
Prospect needs a small bonus to give it an edge in gas mining over the Venture.
Endurance probably needs a Gas Intake bonus if sent gas mining. So it can be a competitive alternative to both. But still be preferred for Ice, while the Prospect would Mining/Gas. The Venture and possible in betweens are good for multirole operations but not specialized Ice mining.
Both Barge and Expedition Frigate Lines need an interest dragging ship available to Alphas. So it draws their attention and skill capacities to consider where they want to go. Also there needs to be an ORE [ore hauling industrial] with much more expanded capacities than a Miasmos or DST. Still will be Omega but will be a preferred ship for dangerous mass mining transfers and market runs.
Also a specialized Light Ore Command ship needs to fill in a roll, so players will use them more aggressively in support of Expedition Frigates and Small Ninja Mining gangs, or to boost the Ventures and etc. Possibly could be tied to Expedition Frigate Skills to unlock.
That is where some of the weaknesses of the ORE line are kind of glaring.